Preliminary Validation of a General Factor Model of Chronic Overlapping Pain Conditions.

Chronic overlapping pain conditions (COPCs) by definition, frequently co-occur, perhaps reflecting their shared etiologies. Their overlapping nature presents a methodological challenge, possibly masking associations between COPCs and health outcomes attributable to either general or specific processes. To address this challenge, we used population-based cohort data to evaluate the predictive validity of a bifactor model of 9 self-reported COPCs by assessing its association with incident pain-related clinical diagnoses; pain-relevant pharmacotherapy; and other health outcomes. We obtained data from a 2005 to 2006 study of Swedish adult twins linked with health data from nationwide registers through 2016 (N = 25,418). We then fit a bifactor model comprising a general COPC factor and 2 independent specific factors measuring pain-related somatic symptoms and neck and shoulder pain. Accounting for age, biological sex, and cancer, the general factor was associated with increased risk of all pain-related outcomes (eg, COPC diagnosis adjusted odds ratio [aOR], 1.71; 95% confidence interval [1.62, 1.81]), most mental health-related outcomes (eg, depression aOR, 1.72 [1.60, 1.85]), and overdose and mortality (eg, all-cause mortality aOR, 1.25 [1.09, 1.43]). The somatic symptoms specific factor was associated with pain-relevant pharmacotherapy (eg, prescribed opioids aOR, 1.25 [1.15, 1.36]), most mental health-related outcomes (eg, depression aOR, 1.95 [1.70, 2.23]), and overdose (eg, nonfatal overdose aOR, 1.66 [1.31, 2.10]). The neck and shoulder pain-specific factor was weakly and inconsistently associated with the outcomes. Findings provide initial support for the validity and utility of a general-factor model of COPCs as a tool to strengthen understanding of co-occurrence, etiology, and consequences of chronic pain. PERSPECTIVE: This article presents associations between a novel measurement model of COPCs and various health outcomes. Findings provide support for measuring pain across multiple domains rather than only measuring pain specific to one physical location in both research and clinical contexts.

Medication utilization in traumatic brain injury patients-insights from a population-based matched cohort study.

Introduction: Traumatic brain injury (TBI) is associated with health problems across multiple domains and TBI patients are reported to have high rates of medication use. However, prior evidence is thin due to methodological limitations. Our aim was thus to examine the use of a wide spectrum of medications prescribed to address pain and somatic conditions in a population-based cohort of TBI patients, and to compare this to a sex- and age-matched cohort. We also examined how patient factors such as sex, age, and TBI severity were associated with medication use. Methods: We assessed Swedish nationwide registers to include all individuals treated for TBI in hospitals or specialist outpatient care between 2006 and 2012. We examined dispensed prescriptions for eight different non-psychotropic medication classes for the 12 months before, and 12 months after, the TBI. We applied a fixed-effects model to compare TBI patients with the matched population cohort. We also stratified TBI patients by sex, age, TBI severity and carried out comparisons using a generalized linear model. Results: We identified 239,425 individuals with an incident TBI and 239,425 matched individuals. TBI patients were more likely to use any medication [Odds ratio (OR) = 2.03, 95% Confidence Interval (CI) = 2.00-2.05], to present with polypharmacy (OR = 1.96, 95% CI = 1.90-2.02), and to use each of the eight medication classes before their TBI, as compared to the matched population cohort. Following the TBI, TBI patients were more likely to use any medication (OR = 1.83, 95% CI = 1.80-1.86), to present with polypharmacy (OR = 1.74, 95% CI = 1.67-1.80), and to use all medication classes, although differences were attenuated. However, differences increased for antibiotics/antivirals (OR = 2.02, 95% CI = 1.99-2.05) and NSAIDs/antirheumatics (OR = 1.62, 95% CI = 1.59-1.65) post-TBI. We also found that females and older patients were more likely to use medications after their TBI than males and younger patients, respectively. Patients with more severe TBIs demonstrated increased use of antibiotics/ antivirals and NSAIDs/antirheumatics than those with less severe TBIs. Discussion: Taken together, our results point to poor overall health in TBI patients, suggesting that medical follow-up should be routine, particularly in females with TBI, and include a review of medication use to address potential polypharmacy.

All cause and cause specific mortality in obsessive-compulsive disorder: nationwide matched cohort and sibling cohort study.

OBJECTIVE: To estimate the risk of all cause and cause specific mortality in people with obsessive-compulsive disorder (OCD) compared with matched unaffected people from the general population and with their unaffected siblings. DESIGN: Population based matched cohort and sibling cohort study. SETTING: Register linkage in Sweden. PARTICIPANTS: Population based cohort including 61 378 people with OCD and 613 780 unaffected people matched (1:10) on sex, birth year, and county of residence; sibling cohort consisting of 34 085 people with OCD and 47 874 unaffected full siblings. Cohorts were followed up for a median time of 8.1 years during the period from 1 January 1973 to 31 December 2020. MAIN OUTCOME MEASURES: All cause and cause specific mortality. RESULTS: 4787 people with OCD and 30 619 unaffected people died during the study period (crude mortality rate 8.1 and 5.1 per 1000 person years, respectively). In stratified Cox proportional hazards models adjusted for birth year, sex, county, migrant status (born in Sweden versus abroad), and sociodemographic variables (latest recorded education, civil status, and family income), people with OCD had an increased risk of all cause mortality (hazard ratio 1.82, 95% confidence interval 1.76 to 1.89) and mortality due to natural causes (1.31, 1.27 to 1.37) and unnatural causes (3.30, 3.05 to 3.57). Among the natural causes of death, those due to endocrine, nutritional, and metabolic diseases, mental and behavioural disorders, and diseases of the nervous, circulatory, respiratory, digestive, and genitourinary systems were higher in the OCD cohort. Conversely, the risk of death due to neoplasms was lower in the OCD cohort compared with the unaffected cohort. Among the unnatural causes, suicide showed the highest hazard ratio, followed by accidents. The results were robust to adjustment for psychiatric comorbidities and familial confounding. CONCLUSIONS: Non-communicable diseases and external causes of death, including suicides and accidents, were major contributors to the risk of mortality in people with OCD. Better surveillance, prevention, and early intervention strategies should be implemented to reduce the risk of fatal outcomes in people with OCD.

Age-related physical health of older autistic adults in Sweden: a longitudinal, retrospective, population-based cohort study.

BACKGROUND: Research of health outcomes in older autistic adults (≥45 years) is concerningly scarce, and little is known about whether intellectual disability and sex affect the health outcomes of this population. The aim of this study was to investigate the association between autism and physical health conditions in older adults and to examine these associations by intellectual disability and sex. METHODS: We conducted a longitudinal, retrospective, population-based cohort study of the Swedish population born between Jan 1, 1932, and Dec 31, 1967, using linked data from the nationwide Total Population Register and the National Patient Register. We excluded individuals who died or emigrated before the age of 45 years, or with any chromosomal abnormalities. Follow-up started at age 45 years for all individuals, and ended at emigration, death, or Dec 31, 2013 (the latest date of available follow-up), whichever was soonest. Diagnoses of autism, intellectual disability, 39 age-related physical conditions, and five types of injury (outcomes) were obtained from the National Patient Register. For each outcome, we calculated 25-year cumulative incidence and used Cox models to estimate hazard ratios (HRs). All analyses were repeated separately by intellectual disability and sex. FINDINGS: Of 4 200 887 older adults (2 063 718 women [49·1%] and 2 137 169 men [50·9%]) in the study cohort, 5291 (0·1%) had a diagnosis of autism recorded in the National Patient Register. Older autistic adults (median follow-up 8·4 years [IQR 4·2-14·6]) had higher cumulative incidence and HRs of various physical conditions and injuries than their non-autistic counterparts (median follow-up 16·4 years [8·2-24·4]). In autistic individuals, the highest cumulative incidence was observed for bodily injuries (50·0% [95% CI 47·6-52·4]). Conditions that autistic adults were at higher risk of than were non-autistic adults included heart failure (HR 1·89 [95% CI 1·61-2·22]), cystitis (2·03 [1·66-2·49]), glucose dysregulation (2·96 [2·04-4·29]), iron deficiency anaemia (3·12 [2·65-3·68]), poisoning (4·63 [4·13-5·18]), and self-harm (7·08 [6·24-8·03]). These increased risks mainly persisted regardless of intellectual disability or sex. INTERPRETATION: Our data indicate that older autistic adults are at substantially increased risk of age-related physical conditions and injuries compared with non-autistic adults. These findings highlight the need for collaborative efforts from researchers, health services, and policy makers to provide older autistic individuals with the necessary support to attain healthy longevity and a high quality of life. FUNDING: Swedish Research Council, Servier Affaires Medicales. TRANSLATION: For the Swedish translation of the abstract see Supplementary Materials section.

Educational Outcomes in Children and Adolescents With Type 1 Diabetes and Psychiatric Disorders.

Importance: Research shows that children and adolescents with type 1 diabetes (T1D), compared with their peers without diabetes, have a greater risk of psychiatric disorders. However, no study has comprehensively examined whether having psychiatric disorders is associated with educational outcomes in children and adolescents with T1D. Objective: To investigate educational outcomes in children and adolescents with T1D with and without psychiatric disorders. Design, Setting, and Participants: This cohort study used data from multiple Swedish registers. The main study cohort included individuals born in Sweden between January 1, 1973, and December 31, 1997, who were followed up from birth through December 31, 2013. Data analyses were conducted from March 1 to June 30, 2022. Exposures: Type 1 diabetes and psychiatric disorders (including neurodevelopmental disorders, depression, anxiety disorders, eating disorders, bipolar disorder, psychotic disorder, and substance misuse) diagnosed before 16 years of age. Main Outcomes and Measures: Achieving educational milestones (completing compulsory school [primary and lower secondary education], being eligible to and finishing upper secondary school, and starting and finishing university) and compulsory school performances. Results: Of 2 454 862 individuals (51.3% male), 13 294 (0.5%; 53.9% male) were diagnosed with T1D (median [IQR] age at diagnosis, 9.5 [6.0-12.5] years), among whom 1012 (7.6%) also had at least 1 psychiatric disorder. Compared with healthy individuals (without T1D and psychiatric disorders), individuals with T1D alone had slightly lower odds of achieving the examined educational milestones. However, those with both T1D and any psychiatric disorder had much lower odds of achieving milestones, including completing compulsory school (odds ratio [OR], 0.17; 95% CI, 0.13-0.21), being eligible for (OR, 0.25; 95% CI, 0.21-0.30) and finishing (OR, 0.19; 95% CI, 0.14-0.26) upper secondary school, and starting (OR, 0.36; 95% CI, 0.29-0.46) and finishing (OR, 0.30; 95% CI, 0.20-0.47) university. They also showed lower grade point averages for compulsory school subjects. These findings remained similar in sibling comparison analyses, suggesting independence from familial confounding. Conclusions and Relevance: In this cohort study of Swedish-born children and adolescents, those with T1D alone had minor difficulties with their educational outcomes, whereas those with both T1D and psychiatric disorders had universal long-term educational underachievement. These findings highlight the importance of identifying psychiatric disorders in pediatric patients with T1D and the need for targeted educational intervention and support to minimize the education gap between the affected children and their peers.

Maternal Serotonergic Antidepressant Use in Pregnancy and Risk of Seizures in Children.

OBJECTIVE: To evaluate whether children born to women who use serotonergic antidepressants during pregnancy have higher risk of neonatal seizures and epilepsy. METHODS: We used Swedish register-based data to examine associations between maternal-reported use of selective-serotonin reuptake inhibitor (SSRI) and selective serotonin-norepinephrine reuptake inhibitors (SNRI) in pregnancy and diagnosis of neonatal seizures and/or epilepsy in over 1.2 million children. To account for systematic differences between exposed and unexposed children we adjusted for a wide range of measured confounders. After first evaluating the role of maternal indication for SSRI/SNRI use (i.e., depression and anxiety) and parental epilepsy, we adjusted for remaining parental background factors (e.g., age, co-morbidities, education, and family socioeconomic indices) and pregnancy-specific characteristics (e.g., maternal use of other psychotropic medications and tobacco smoking in early pregnancy). RESULTS: Compared with all other children, children of women that reported use of SSRI/SNRI in pregnancy had an elevated risk of neonatal seizures and epilepsy (risk ratio [RR]=1.41, 95% confidence interval [CI]=1.03-1.94; hazard ratio [HR]=1.21, 95% CI=1.03-1.43 respectively). The estimates of association were attenuated by adjustment for maternal indications for SSRI/SNRI use (RR=1.30, 95% CI=0.94-1.79; HR = 1.13, 95% CI = 0.95-1.33), but not by additional adjustment for parental history of epilepsy. Full adjustment for all measured parental and pregnancy-specific factors resulted in substantial attenuation of the remaining associations (RR = 1.10, 95% CI = 0.79-1.53; HR = 0.96, 95% CI = 0.81-1.14). CONCLUSIONS: The present study found no support for the concern that maternal SSRI/SNRI use in pregnancy increases children's risk for neonatal seizures or epilepsy. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that exposure to SSRI/SNRI's in the first trimester of pregnancy is not associated with an increased incidence of neo-natal seizures/epilepsy.

The role of ADHD genetic risk in mid-to-late life somatic health conditions.

Growing evidence suggests that ADHD, an early onset neurodevelopmental disorder, is associated with poor somatic health in adulthood. However, the mechanisms underlying these associations are poorly understood. Here, we tested whether ADHD polygenic risk scores (PRS) are associated with mid-to-late life somatic health in a general population sample. Furthermore, we explored whether potential associations were moderated and mediated by life-course risk factors. We derived ADHD-PRS in 10,645 Swedish twins born between 1911 and 1958. Sixteen cardiometabolic, autoimmune/inflammatory, and neurological health conditions were evaluated using self-report (age range at measure 42-88 years) and clinical diagnoses defined by International Classification of Diseases codes in national registers. We estimated associations of ADHD-PRS with somatic outcomes using generalized estimating equations, and tested moderation and mediation of these associations by four life-course risk factors (education level, body mass index [BMI], tobacco use, alcohol misuse). Results showed that higher ADHD-PRS were associated with increased risk of seven somatic outcomes (heart failure, cerebro- and peripheral vascular disease, obesity, type 1 diabetes, rheumatoid arthritis, and migraine) with odds ratios ranging 1.07 to 1.20. We observed significant mediation effects by education, BMI, tobacco use, and alcohol misuse, primarily for associations of ADHD-PRS with cardiometabolic outcomes. No moderation effects survived multiple testing correction. Our findings suggests that higher ADHD genetic liability confers a modest risk increase for several somatic health problems in mid-to-late life, particularly in the cardiometabolic domain. These associations were observable in the general population, even in the absence of medical treatment for ADHD, and appear to be in part mediated by life-course risk factors.

Associations of parental and perinatal factors with subsequent risk of stress-related disorders: a nationwide cohort study with sibling comparison.

Little is known about the contribution of pregnancy-related parental and perinatal factors to the development of stress-related disorders. We aimed to investigate whether parental/perinatal adversities entail higher risks of stress-related disorders in the offspring, later in life, by accounting for genetic and early environmental factors. Based on the nationwide Swedish registers, we conducted a population-based cohort study of 3,435,747 singleton births (of which 2,554,235 were full siblings), born 1973-2008 and survived through the age of 5 years. Using both population- and sibling designs, we employed Cox regression to assess the association between parental and perinatal factors with subsequent risk of stress-related disorders. We identified 55,511 individuals diagnosed with stress-related disorders in the population analysis and 37,433 in the sibling analysis. In the population-based analysis we observed increased risks of stress-related disorders among offspring of maternal/paternal age <25, single mothers, parity ≥4, mothers with BMI ≥ 25 or maternal smoking in early pregnancy, gestational diabetes, and offspring born moderately preterm (GA 32-36 weeks), or small-for-gestational-age. These associations were significantly attenuated toward null in the sibling analysis. Cesarean-section was weakly associated with offspring stress-related disorders in population [hazard ratio (HR) 1.09, 95% confidence interval (CI) 1.06-1.12] and sibling analyses (HR 1.10, 95% CI 1.02-1.20). Our findings suggest that most of the observed associations between parental and perinatal factors and risk of stress-related disorders in the population analysis are driven by shared familial environment or genetics, and underscore the importance of family designs in epidemiological studies on the etiology of psychiatric disorders.

Association of Intellectual Disability With All-Cause and Cause-Specific Mortality in Sweden.

Importance: Knowledge of the health challenges and mortality in people with intellectual disability (ID) should guide health policies and practices in contemporary society. Objective: To examine premature mortality in individuals with ID. Design, Setting, and Participants: This population-based longitudinal cohort study obtained data from several national health care, education, and population registers in Sweden. Two registers were used to identify individuals with ID: the National Patient Register and the Halmstad University Register on Pupils With Intellectual Disability. Two cohorts were created: cohort 1 comprised young adults (born between 1980 and 1991) with mild ID, and cohort 2 comprised individuals (born between 1932 and 2013) with mild ID or moderate to profound ID; each cohort had matched reference cohorts. Data analyses were conducted between June 1, 2020, and March 31, 2021. Exposures: Mild or moderate to profound ID. Main Outcomes and Measures: The primary outcome was overall (all-cause) mortality, and the secondary outcomes were cause-specific mortality and potentially avoidable mortality. Results: Cohort 1 included 13 541 young adults with mild ID (mean [SD] age at death, 24.53 [3.66] years; 7826 men [57.8%]), and its matched reference cohort consisted of 135 410 individuals. Cohort 2 included 24 059 individuals with mild ID (mean [SD] age at death, 52.01 [16.88] years; 13 649 male individuals [56.7%]) and 26 602 individuals with moderate to profound ID (mean [SD] age at death, 42.16 [21.68] years; 15 338 male individuals [57.7%]); its matched reference cohorts consisted of 240 590 individuals with mild ID and 266 020 with moderate to profound ID. Young adults with mild ID had increased overall mortality risk compared with the matched reference cohort (odds ratio [OR], 2.86; 95% CI, 2.33-3.50), specifically excess mortality in neoplasms (OR, 3.58; 95% CI, 2.02-6.35), diseases of the nervous system (OR, 40.00; 95% CI, 18.43-86.80) and circulatory system (OR, 9.24; 95% CI, 4.76-17.95). Among deaths that were amenable to health care (OR, 7.75; 95% CI, 4.85-12.39), 55% were attributed to epilepsy. In cohort 2, increased risk of overall mortality was observed among both individuals with mild ID (OR, 6.21; 95% CI, 5.79-6.66) and moderate to profound ID (OR, 13.15; 95% CI, 12.52-13.81) compared with the matched reference cohorts. Those with moderate to profound ID had a higher risk in several cause-of-death categories compared with those with mild ID or the matched reference cohort. Adjustment for epilepsy and congenital malformations attenuated the associations. The relative risk of premature death was higher in women (OR, 6.23; 95% CI, 4.42-8.79) than in men (OR, 1.99; 95% CI, 1.53-2.60), but the absolute risk of mortality was similar (0.9% for women vs 0.9% for men). Conclusions and Relevance: This study found excess premature mortality and high risk of deaths with causes that were potentially amenable to health care intervention among people with ID. This finding suggests that this patient population faces persistent health challenges and inequality in health care encounters.

Evidence for a Causal Relationship Between Academic Achievement and Cigarette Smoking.

INTRODUCTION: Academic achievement (AA) is associated with smoking rates. Can we determine the degree to which this relationship is likely a causal one? METHODS: We predict smoking in male conscripts (mean age 18.2) assessed from 1984 to 1991 (N = 233 248) and pregnant females (mean age 27.7) receiving prenatal care 1972-1990 (N = 494 995) from AA assessed in all students at 16. Instrumental variable (IV) analyses used the instrument month-of-birth as in each school year, older children have high AA. Co-relative analyses used AA-smoking associations in the population, cousins and siblings to predict the AA-smoking relationship in MZ twins, thereby controlling for familial confounding. RESULTS: In males, higher AA was associated with a substantial decrease in risk for smoking (odds ratio [OR] [95% confidence intervals [CIs]] per standard deviation [SD] = 0.41 [0.40-0.41]) while the parallel figures obtain from our IV and co-relative analyses were 0.47 (0.39-0.57) and 0.51 (0.43-0.60), respectively. In females, these figures for pre-pregnancy smoking were, respectively, 0.39 (0.39-0.39), 0.50 (0.46-0.54) and 0.54 (0.51-0.58). Results for heavy versus light smoking suggested a causal effect but were inconsistent across methods. However, among females smoking prior to pregnancy, AA predicted a reduced risk for continued smoking with ORs for uncontrolled, IV, and co-relative analyses equaling, respectively, were 0.54 (0.53-0.55) 0.68 (0.56-0.82) and 0.78 (0.66-0.91), respectively. CONCLUSIONS: Two different methods produced consistent evidence that higher AA has a causal effect on reducing smoking rates and increasing cessation rates in smoking pregnant females. Improving AA may result in meaningful gains in population health through reduced smoking. IMPLICATIONS: This study provides consistent evidence across two different methods that high AA is causally related to reduced rates of smoking and increasing rates of smoking cessation among pregnant women. Our results suggest that interventions that improve educational achievement in adolescence would reduce tobacco consumption, thereby improving public health.

A population-based study of concurrent prescriptions of opioid analgesic and selective serotonin reuptake inhibitor medications during pregnancy and risk for adverse birth outcomes.

BACKGROUND: Pregnant women with painful conditions often have mental health problems, including depression and anxiety. Co-morbid conditions may cause pregnant women to use multiple medications, although safety of such practice is poorly understood. OBJECTIVES: We investigated the influence of combined prescriptions of opioid analgesics and selective serotonin reuptake inhibitors (SSRIs) during pregnancy on two adverse birth outcomes. METHODS: We analysed Swedish population-based births (n = 688 914) between 2007 and 2013. Using national registers, we obtained data on filled medication prescriptions, birth outcomes, and a wide range of parental characteristics. We estimated preterm birth and small-for-gestational-age risk following independent or combined prescriptions of the two medications compared with no filled prescriptions for either medication. We adjusted for confounders using inverse probability of treatment weights. RESULTS: After adjusting for confounders, preterm birth risk was higher among women with opioid analgesic prescriptions only (5.9%; risk ratio [RR] 1.27, 95% confidence interval [CI] 1.22, 1.33), SSRIs only (6.2%; RR 1.34, 95% CI 1.27, 1.42), and both medications (7.8%; RR 1.70, 95% CI 1.47, 1.96) compared with unexposed women (4.6%). The interaction between the medications on preterm birth was small (risk difference [RD] 0.4%, 95% CI -0.8%, 1.6%); relative excess risk due to interaction [RERI] 0.09, 95% CI -0.17, 0.34; RR 1.00, 95% CI 0.85, 1.17). For small for gestational age, risk was approximately 2% across all groups, and there was no interaction between the medications (RD 0.3%, 95% CI -0.4%, 1.1%); RERI 0.15, 95% CI -0.16, 0.47; RR 1.15, 95% CI 0.87, 1.52). CONCLUSIONS: Compared with unexposed pregnancies, those with either medication alone had a small increased risk for preterm birth but no increased risk for small for gestational age. The magnitude of associations with combined exposure to both medications were not greater than the sum of the associations with each medication considered individually.

Mortality and major disease risk among migrants of the 1991-2001 Balkan wars to Sweden: A register-based cohort study.

BACKGROUND: In recent decades, millions of refugees and migrants have fled wars and sought asylum in Europe. The aim of this study was to quantify the risk of mortality and major diseases among migrants during the 1991-2001 Balkan wars to Sweden in comparison to other European migrants to Sweden during the same period. METHODS AND FINDINGS: We conducted a register-based cohort study of 104,770 migrants to Sweden from the former Yugoslavia during the Balkan wars and 147,430 migrants to Sweden from 24 other European countries during the same period (1991-2001). Inpatient and specialized outpatient diagnoses of cardiovascular disease (CVD), cancer, and psychiatric disorders were obtained from the Swedish National Patient Register and the Swedish Cancer Register, and mortality data from the Swedish Cause of Death Register. Adjusting for individual-level data on sociodemographic characteristics and emigration country smoking prevalence, we used Cox regressions to contrast risks of health outcomes for migrants of the Balkan wars and other European migrants. During an average of 12.26 years of follow-up, being a migrant of the Balkan wars was associated with an elevated risk of being diagnosed with CVD (HR 1.39, 95% CI 1.34-1.43, p < 0.001) and dying from CVD (HR 1.45, 95% CI 1.29-1.62, p < 0.001), as well as being diagnosed with cancer (HR 1.16, 95% CI 1.08-1.24, p < 0.001) and dying from cancer (HR 1.27, 95% CI 1.15-1.41, p < 0.001), compared to other European migrants. Being a migrant of the Balkan wars was also associated with a greater overall risk of being diagnosed with a psychiatric disorder (HR 1.19, 95% CI 1.14-1.23, p < 0.001), particularly post-traumatic stress disorder (HR 9.33, 95% CI 7.96-10.94, p < 0.001), while being associated with a reduced risk of suicide (HR 0.68, 95% CI 0.48-0.96, p = 0.030) and suicide attempt (HR 0.57, 95% CI 0.51-0.65, p < 0.001). Later time period of migration and not having any first-degree relatives in Sweden at the time of immigration were associated with greater increases in risk of CVD and psychiatric disorders. Limitations of the study included lack of individual-level information on health status and behaviors of migrants at the time of immigration. CONCLUSIONS: Our findings indicate that migrants of the Balkan wars faced considerably elevated risks of major diseases and mortality in their first decade in Sweden compared to other European migrants. War migrants without family members in Sweden or with more recent immigration may be particularly vulnerable to adverse health outcomes. Results underscore that persons displaced by war are a vulnerable group in need of long-term health surveillance for psychiatric disorders and somatic disease.

Modeling Etiology of Smoking During Pregnancy in Swedish Twins, Full-, and Half-Siblings, Reared Together and Apart.

INTRODUCTION: Using Swedish nationwide registry data, we investigated the contribution of genetic and environmental risk factors to the etiology of smoking status across stages of pregnancy with increasing degrees of social and psychological pressure to reduce or quit smoking, by twin and sibling modeling. AIMS AND METHODS: Smoking status was available before, and during early and late pregnancy from the Medical Birth Register. Twin, full-, and half-sibling pairs, both reared together and apart, born between 1960 and 1990 were obtained from national twin and genealogical registers. Genetic structural equation modeling in OpenMx was applied to the population-based data to estimate shared genetic and/or environmental covariance across stages of pregnancy, accounting for maternal birth cohort and age at pregnancy. RESULTS: Analyses of paired data on 258 749 individuals suggested that risk factors for smoking status changed across stages of pregnancy. Results predicted substantial heritability (60-70%) and moderate contributions of shared environmental factors (10-15%) for smoking status. Whilst the same shared environmental factors were amplified from before pregnancy to late pregnancy, new primarily unique environmental factors explained ~10% of the variance during early pregnancy which was carried forward to late pregnancy. CONCLUSIONS: Using registry data on women across pregnancy, we replicated that smoking status is highly heritable. Furthermore, we found support for increased impact of shared environmental factors during pregnancy of factors already present prior to pregnancy, and an independent set of mostly new unique environmental factors that may be triggered by increased social pressure to reduce or quit smoking during pregnancy. IMPLICATIONS: As new factors partially explain smoking status during pregnancy and the effects of familial factors increase across pregnancy, efforts to prevent or reduce smoking during pregnancy should receive continued attention, with a focus on both the individual and the family unit.

Physical health in children with neurodevelopmental disorders.

With increasing numbers of children being diagnosed with neurodevelopmental disorders (NDDs) attention has been drawn to these children's physical health. We aimed to identify the prevalence of defined physical problems (epilepsy, migraine, asthma, cancer, diabetes, psoriasis, lactose intolerance, celiac disease, diarrhea, constipation, daytime enuresis, encopresis) in a nationwide population of 9- and 12-year-old twins subdivided into those with and without indications of NDDs. Parents of 28,058 twins participated in a well-validated telephone interview regarding their children's mental health and answered questions about their physical problems. The results indicate a high rate of physical problems in children with NDDs, particularly in those with indications of the presence of combinations of several NDDs.

Aggressive behaviour in childhood and adolescence: the role of smoking during pregnancy, evidence from four twin cohorts in the EU-ACTION consortium.

BACKGROUND: Maternal smoking during pregnancy (MSDP) has been linked to offspring's externalizing problems. It has been argued that socio-demographic factors (e.g. maternal age and education), co-occurring environmental risk factors, or pleiotropic genetic effects may account for the association between MSDP and later outcomes. This study provides a comprehensive investigation of the association between MSDP and a single harmonized component of externalizing: aggressive behaviour, measured throughout childhood and adolescence. METHODS: Data came from four prospective twin cohorts - Twins Early Development Study, Netherlands Twin Register, Childhood and Adolescent Twin Study of Sweden, and FinnTwin12 study - who collaborate in the EU-ACTION consortium. Data from 30 708 unrelated individuals were analysed. Based on item level data, a harmonized measure of aggression was created at ages 9-10; 12; 14-15 and 16-18. RESULTS: MSDP predicted aggression in childhood and adolescence. A meta-analysis across the four samples found the independent effect of MSDP to be 0.4% (r = 0.066), this remained consistent when analyses were performed separately by sex. All other perinatal factors combined explained 1.1% of the variance in aggression across all ages and samples (r = 0.112). Paternal smoking and aggressive parenting strategies did not account for the MSDP-aggression association, consistent with the hypothesis of a small direct link between MSDP and aggression. CONCLUSIONS: Perinatal factors, including MSDP, account for a small portion of the variance in aggression in childhood and adolescence. Later experiences may play a greater role in shaping adolescents' aggressive behaviour.

Illicit Drug Use, Cigarette Smoking, and Eating Disorder Symptoms: Associations in an Adolescent Twin Sample.

OBJECTIVE: Twin studies have shown that genetic factors in part explain the established relation between alcohol use (i.e., problematic use or abuse/dependence) and eating disorder symptoms in adolescent and adult females. However, studies have yet to elucidate if there are similar shared genetic factors between other aspects of substance involvement, such as illicit drug use and repeated cigarette smoking. METHOD: For those sex-specific phenotypic correlations above our threshold of .20, we used a behavioral genetic design to examine potential shared genetic overlap between self-reported lifetime illicit drug use and repeated cigarette smoking and the eating disorder symptoms of drive for thinness (DT), bulimia (BU), and body dissatisfaction (BD), as assessed with the Eating Disorder Inventory-II, in 16- to 17-year-old female and male twin pairs. RESULTS: Only phenotypic correlations with illicit drug use met our threshold for twin modeling. Small to moderate genetic correlations were observed between illicit drug use and BU in both girls and boys and between illicit drug use and DT in girls. CONCLUSIONS: Similar etiological factors are at play in the overlap between illicit drug use and certain eating disorder symptoms in girls and boys during adolescence, such that genetic factors are important for covariance. Specifically, illicit drug use was associated with bulimia nervosa symptoms in girls and boys, which parallels previous substance use research finding a genetic overlap between alcohol use and bulimia nervosa symptoms. Future research should prospectively examine developmental trajectories to further understand the etiological overlap between substance involvement and eating disorder symptoms.

Parental nicotine replacement therapy and offspring bronchitis/bronchiolitis and asthma - a nationwide population-based cohort study.

BACKGROUND: Prior evidence shows that environmental tobacco smoke is a risk factor for respiratory tract infections, wheeze, and asthma. Nicotine replacement therapy has been shown to increase smoking cessation. However, no prior studies have explored if parental use decreases the risk of bronchitis/bronchiolitis and asthma in the offspring. OBJECTIVE: To examine whether nicotine replacement therapy varenicline, given to parents, was associated with a reduction in bronchitis/bronchiolitis and/or asthma in their children. METHODS: This study is a population-based cohort study, linking data from nationwide registers, and using a within-individual design that minimizes selection effects and controls for time-invariant confounding factors. Participants included 37,420 parents with a collected prescription of varenicline with 72,392 offspring <18 years of age. Exposure was defined as collected prescriptions of varenicline among the parents. Primary outcomes were offspring hospital visits for bronchitis/bronchiolitis (ICD10: J20 or J21) and offspring hospital visits for asthma (ICD10: J45). RESULTS: Parental varenicline treatment was associated with a lower rate of visits for bronchitis/bronchiolitis in their children (incidence rate ratio [IRR]=0.67; 95% CI=0.50-0.91), but no association was found for asthma (IRR=1.08; 95% CI=0.97-1.19). The rate reduction of bronchitis/bronchiolitis was similar when we restricted data to children aged 0-3 years (IRR=0.71; 95% CI=0.52-0.97) and to maternal varenicline treatment (IRR=0.64; 95% CI=0.43-0.96). When restricting the outcomes to unplanned visits only (ie, excluding booked appointments, followups, and referrals), no associations were found (IRR=0.72, 95% CI=0.51-1.02). CONCLUSION: In this cohort study, nicotine replacement treatment in parents was associated with reduced hospital visits for bronchitis/bronchiolitis in their children.

Association Between Maternal Smoking During Pregnancy and Severe Mental Illness in Offspring.

Importance: Several recent population-based studies have linked exposure to maternal smoking during pregnancy to increased risk of severe mental illness in offspring (eg, bipolar disorder, schizophrenia). It is not yet clear, however, whether this association results from causal teratogenic effects or from confounding influences shared by smoking and severe mental illness. Objective: To examine the association between smoking during pregnancy and severe mental illness in offspring, adjusting for measured covariates and unmeasured confounding using family-based designs. Design, Setting, and Participants: This study analyzed population register data through December 31, 2013, for a cohort of 1 680 219 individuals born in Sweden from January 1, 1983, to December 31, 2001. Associations between smoking during pregnancy and severe mental illness in offspring were estimated with adjustment for measured covariates. Cousins and siblings who were discordant on smoking during pregnancy and severe mental illness were then compared, which helped to account for unmeasured genetic and environmental confounding by design. Exposures: Maternal self-reported smoking during pregnancy, obtained from antenatal visits. Main Outcomes and Measures: Severe mental illness, with clinical diagnosis obtained from inpatient and outpatient visits and defined using International Classification of Diseases codes for bipolar disorder and schizophrenia spectrum disorders. Results: Of the 1 680 219 offspring included in the analysis, 816 775 (48.61%) were female. At the population level, offspring exposed to moderate and high levels of smoking during pregnancy had greater severe mental illness rates than did unexposed offspring (moderate smoking during pregnancy: hazard ratio [HR], 1.25; 95% CI, 1.19-1.30; high smoking during pregnancy: HR, 1.51; 95% CI, 1.44-1.59). These associations decreased in strength with increasing statistical and methodologic controls for familial confounding. In sibling comparisons with within-family covariates, associations were substantially weaker and nonsignificant (moderate smoking during pregnancy: HR, 1.09; 95% CI, 0.94-1.26; high smoking during pregnancy: HR, 1.14; 95% CI, 0.96-1.35). The pattern of associations was consistent across subsets of severe mental illness disorders and was supported by further sensitivity analyses. Conclusions and Relevance: This population- and family-based study failed to find support for a causal effect of smoking during pregnancy on risk of severe mental illness in offspring. Rather, these results suggest that much of the observed population-level association can be explained by measured and unmeasured factors shared by siblings.

A Genetic Epidemiological Mega Analysis of Smoking Initiation in Adolescents.

INTRODUCTION: Previous studies in adolescents were not adequately powered to accurately disentangle genetic and environmental influences on smoking initiation (SI) across adolescence. METHODS: Mega-analysis of pooled genetically informative data on SI was performed, with structural equation modeling, to test equality of prevalence and correlations across cultural backgrounds, and to estimate the significance and effect size of genetic and environmental effects according to the classical twin study, in adolescent male and female twins from same-sex and opposite-sex twin pairs (N = 19 313 pairs) between ages 10 and 19, with 76 358 longitudinal assessments between 1983 and 2007, from 11 population-based twin samples from the United States, Europe, and Australia. RESULTS: Although prevalences differed between samples, twin correlations did not, suggesting similar etiology of SI across developed countries. The estimate of additive genetic contributions to liability of SI increased from approximately 15% to 45% from ages 13 to 19. Correspondingly, shared environmental factors accounted for a substantial proportion of variance in liability to SI at age 13 (70%) and gradually less by age 19 (40%). CONCLUSIONS: Both additive genetic and shared environmental factors significantly contribute to variance in SI throughout adolescence. The present study, the largest genetic epidemiological study on SI to date, found consistent results across 11 studies for the etiology of SI. Environmental factors, especially those shared by siblings in a family, primarily influence SI variance in early adolescence, while an increasing role of genetic factors is seen at later ages, which has important implications for prevention strategies. IMPLICATIONS: This is the first study to find evidence of genetic factors in liability to SI at ages as young as 12. It also shows the strongest evidence to date for decay of effects of the shared environment from early adolescence to young adulthood. We found remarkable consistency of twin correlations across studies reflecting similar etiology of liability to initiate smoking across different cultures and time periods. Thus familial factors strongly contribute to individual differences in who starts to smoke with a gradual increase in the impact of genetic factors and a corresponding decrease in that of the shared environment.